In the present application, fuse (fuse=fusible link) means a structure and/or conductive trace in an integrated circuit and/or a semiconductor device that can be destroyed after manufacturing the semiconductor device and/or processing the same at the wafer level. Thus, for example an electrically conductive connection and/or a fuse conductive trace can be cut, thereby effecting a later change in circuit behavior. Destroying and/or cutting is performed by means of an electrical current surge or a laser spike.
The fuse structures are used, for example, for cutting defective parts of a circuit after completion and/or manufacturing of a semiconductor device, or for trimming properties of finished circuits to a target value later on and/or after the processing of a wafer on which the circuit is deposited. Additionally, fuse structures are used to enable an identification of the individual chips, wherein a special code which can be read out electrically and/or optically is created by separating the fuse and/or cutting the fuse conductive trace.
Since a sealed surface that protects an underlying circuit structure is broken open when destroying the fuse structure, a corrosion problem often arises after destroying the fuse conductive trace. The corrosion occurring due to the prevailing humidity in the surroundings or due to contacting the semiconductor device with an aggressive substance, for example, to process a surface of the semiconductor device in a further method step, can thereby propagate and/or continue along conductive traces and may even result in a breakdown of the circuit.
In order to limit and/or to prevent propagation of the corrosion, a terminal of a fuse conductive trace and/or a contacting of the fuse conductive trace is implemented by buried polysilicon lines that are not in danger of corrosion. Corrosion propagating into the substrate of the semiconductor device then comes to a halt at the polysilicon lines without further parts of the circuit in the semiconductor device being damaged. But since the deeply buried polysilicon lines are used for contacting the fuse conductive trace, it is necessary with a semiconductor device with a conventional fuse structure to create an electric connection via conductors and vias which typically extend in the semiconductor device in a vertical direction. This results in an increase in a resistance of the fuse structure in an order of a few tens of Ohms. At the same time, additional parasitic capacitances arise due to a small distance between the polysilicon lines in the polysilicon level and a substrate on which the circuit structures in the semiconductor device are arranged. The resulting increase in the parasitic capacitances as well as the increase in the resistance are undesired and/or not tolerable when using the fuse structure in semiconductor devices with ultra-high-frequency circuits, such as, for example, a 77 GHz oscillator, because they limit performance and/or capability of the circuit.
Therefore, conventional fuse structures are not suitable for being used in ultra-high-frequency circuits and/or RF circuits, which is why up to now late trimming and/or adjusting of the features of the circuit of high-frequency circuits and/or ultra-high-frequency circuits by means of cutting the fuse conductive trace is not possible.